[antlr-interest] AST - don't get it
Manu
manunews at gmail.com
Wed Nov 8 05:19:02 PST 2006
Hi,
I have understood why is good to build an AST but I don't understand
exactly how the tree builder operators work. For example, I'd expect
the following grammar to generate an AST for the entry: 123 * 456
like:
(START (* 123 456))
but instead it generates:
(NIL (START (* 456)))
where did the 123 go?
grammar Expressions;
options
{
output=AST;
ASTLabelType=CommonTree;
}
tokens
{
START;
}
s : expression EOF -> ^(START expression);
expression: multiplicativeExpression ('+'^^ multiplicativeExpression)*;
multiplicativeExpression: primitiveExpression ('*'^^ primitiveExpression)*;
primitiveExpression: INT_LITERAL;
INT_LITERAL: ('0'..'9')+;
WS: (' ' | '\r' | '\t' | '\n') {channel=99;};
Please help me,
Thanks.
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